Adsorption process and apparatus



May 1, 1951 y c. H. o. BERG 2,550,955

ADSORPTION PROCESS AND APPARATUS Filed Feb. 2l, 1947 2 Sheets-Sheet l /MPRCTL ESS SEPPRTOR cooL/NG /sEcr/o/v T I GHS 55 FEED ,e/cf/ ons oEsoepr/oN 1' *5 sEcr/o/v |9\n soups FEEDER v fzo srEnM e 2 22a; `L/ET1./NE'

, T L/Fr ans Lrgm V25 LowE/Q INVENTOR.

May 1,1951 c. H. o. BERG 2,550,955

ADSORPTIO PROCESS AND APPARATUS Filed Feb. 21, 1947 2 ShQBtS-Sheet 2 n, COOL/NG i i secr/0N a 5. io f 2 i 87 8O En/v Gns 86 85 fr; 88 F 1, 47

a i 145 l 'l Patented lVay l, 1951 ADSDRPTION PROCESS ANI) APPARATUS Clyde H. 0. Berg, Long Beach, Calif., assigner to Union Oil' Company of California, Los Angeles, Calif., a corporation of California Application February 21, 1947, serial No. 730,166

23 Claims. l

This invention relates to a process and apparatus for the continuous separation of normally gaseous mixtures 'by selective adsorption of certain constituents of such mixtures on solid granuIar adsorbents and applies particularly to the separation of gaseous mixtures containing relatively small amounts oi those constituents which are more readily adsorbable on granular charcoal.

The separation of a light gaseous mixture into its constituent parts by the process of selective adsorption oiers many advantages over the conventional separation processes of distillation, extraction, etc. In applying the processes of distillation or extraction to the separation of gaseous mixtures containing constituents of relatively low molecular weight, elevated pressures are required together With abnormally low temperatures to condense the gas into a liquid so that it may be separated by these processes. For example, in thel preparation of pure ethylene by fractional distillation of ethylene-bearing stocks, a fractionator pressure of 385 pounds per square inch and a reiiux temperature of vF. are required. In the preparation of pure methane by asimilar process a pressure between 500 and 600 pounds per square inch and a reiiux temperature of 150 F. are required. The compression and refrigeration of light gaseous mixtures to permit Separation by distillation or extraction are expensive operations and consequently large quantities of gaseous mixtures containing these and other light compounds are often Wasted rather than to perform expensive recovery operations.

The conventional process of gas absorption has disadvantages whichoften render it inapplicable to the separation of light gaseous mixtures because generally the gases of low molecular weight are less soluble in the absorbing medium used in adsorbing compounds of the same class having higher molecular weights. Thus, high pressures of operation are also required in absorption processes tin order to obtain an appreciable concentration of the light gaseous compound in the absorbing medium and to avoid circulation of large quantities of the absorbing medium through the system.

I have previously proposed a method for the separation of gaseous mixtures containing constituents which are difiicultly liqueable because of low critical temperatures and constituents which are not readily soluble in commonly used solvents. By this method such gaseous mixtures may be conveniently and economically separated at moderate temperatures and pressures which involves the application of selective adsorption and desorption.

In general, my previously proposed process of separating gaseous mixtures by continuous selective adsorption on a granular solid adsorbent involves the steps of countercurrently contacting the gaseous mixture with a moving bed of the adsorbent, thereby adsorbing from the mixture those constituents which are more readily adsorbable and leaving as a substantially unadsorbed gas those constituents which are less readily adsorbable. In a moving bed operation, the adsorbent upon which certain of the gaseous constituents have been adsorbed iiows from an adsorption section into a stripping or desorption section wherein the adsorbent is heated and contacted With a stripping gas, such as steam for example, to cause the adsorbed constituents to be liberated. The adsorbent, freed of adsorbed constituents, is subsequently cooled prior to repassage through the adsorption section. In this proposed process of selective adsorption a gaseous mixture may be divided into two separate fractions consisting of a rich gas containing the more readily adsorbable constituents having the higher molecular Weight cr critical temperature and a lean gas containing the less readily adsorbable constituents having the lower molecular weight or critical temperature. The rich gas is obtained by adsorption and subsequent desorption of the more readily adsorbable constituents and the lean gas is obtained by removal from the adsorption section of the less readily adsorbable constituents as a substantially unadsorbed gas.

In a recently proposed improvement in the art of separation of gaseous mixtures by selective adsorption, an adsorption column has been provided which contains two or more rectification sections which permits the separation of the gaseous mixtures into more than two fractions. Such operations are made possible by the utilization` of a reuxing step Within these rectification sections permitting production not only of the lean and rich gases cited above, but also one or more intermediate fractions containing constituents which are of intermediate adsorbability.

By modifications of the previously proposed processes involving selective adsorption almost any gaseous mixture containing constituents of 10W molecular weight or low critical temperature may be conveniently handled and separated into a multiplicity of fractions. The process of selective adsorption is particularly applicable to the separation of gaseous mixtures containing relatively small percentages of the more readily adsorbable constituents, such as those with higher molecular weights or critical temperatures, and it is to the improvement of the last-named operation that my invention, which is hereinafter more fully described, is directed.

Such gaseous mixtures containing relatively small amounts of the more readily adsorbable constituents occur frequently in industrial practice. The separation of certain constituents from this type of gaseous mixture may be exemplified by the recovery of vaporized solvents from air, the recovery of natural gasoline from the natural gas produced simultaneously with crude petroleum, the recovery of carbon dioxide from flue gases, the recovery of sulfur dioxide and sulfur trioxide from sulfur burner iiue gases', the recovery of the equilibrium mixture nitrogen tetroxidenitrogen dioxide occurring in the eiiiuent gases from catalytic air oxidation of ammonia, the separation of methane, or the separation of oxygen, nitrogen, carbon monoxide, carbon dioxide, and water vapor contaminants from impure hydrogen, and many othergaseous mixtures. My process is equally eiective in the recovery of either the major or minor proportions of such gaseous mixtures or both provided that the more readily adsorbable constituent is in the minor proportion, for example, less than about 30 volume per cent. It is particularly well adapted to the separation of gaseous mixtures wherein the more readily adsorbable constituent is present in concentrations less than volume per cent.

In the separation by selective adsorption of such gaseous mixtures containing relatively small amounts of the more readily adsorbable constituents as indicated above, the amount of adsorbent required for each unit volume of the gaseous mixture being separated is relatively small and the volume of gas which passes through the selective adsorption unit, and which is substantially unadsorbed, is relatively large. In order to properly design selective adsorption units which will eiiiciently handle gaseous mixtures containing considerable proportions of gases which are substantially unaclsorbed by the adsorbent, a relatively large cross-sectional area must be provided in the selective adsorption unit at the point in which the critical gas velocity exists. In units designed to treat the type of gaseous mixtures indicated above, this point of critical gas velocity exists in the adsorption section where the gas to be separated is introduced.

In addition, a substantially complete adsorption of the minor amount of more readily adsorbable constituent must be insured in order to produce fractions of the gaseous mixture being treated which are of high purity. The maintenance of a moderate gas velocity through the adsorbent in the adsorption section serves to insure the complete adsorption of the more readily adsorbable constituents, and may be accomplished by providing an adsorption section having a relatively large cross-sectional area. This requirement of a large cross-sectional area in the selective adsorption unit necessitates the use of adsorption towers of relatively large diameter. Because selective adsorption towers are generally between about 70 and 120 feet in height, the construction of a number of large diameter selective adsorption towers to separate large volurnes of a given gaseous mixture is of considerable expense.

It is a particular obj ect to provide an improved selective adsorption process directed tol the sepalight hydrocarbon gases, such as,A i

ration of gaseous mixtures in which the more readily adsorbable constituents of such gaseous mixtures are present in relatively low concentrations. y

Another object of my invention is to provide an improved selective adsorption process by' which such gaseous mixtures may be separated with higher recoveries and at increased economies than heretofore possible.

It is still a further object of my invention to provide in the'selective adsorption process an improved apparatus which is particularly adapted to the separation of gaseous mixtures containing relatively small amounts ci the more readily adsorbable constituents.

Other objects and advantages ci this invention will become apparent to those skilled in the art as the description thereof proceeds.

According to the process of my invention I am able to accomplish the above-*mentioned vobjects by providing in the improved selective adsorp-r tion process, as more fully described hereinafter, a selective adsorption tower having an adsorption section of special construction which permits an increase of about in the feed rate to a selective adsorption tower having a given*v cross-sectional area without impairing either the efliciency or the economy of the process. Furthermore, the special construction of the adsorption section provides a more thorough contact of the adsorbent employed by the gaseous mixture to be separated which results in a more complete and elicient separation with decreased amounts of contaminants in the product streams.

In the selective adsorption tower, the adsorbent such as silica gel, activated alumina, activated charcoal, etc., flows downwardly through a tubu lar cooling section and through a disengaging` section into the adsorption section. The disen-4 gaging section consists of a horizontal tray hav-r ing short tubes extending downward from and attached to the tray in such a manner that the charcoal which flows through the tubes forms a gas space between the lower sur-face of the tray' and the upper surface of the adsorbent flowing from the lower open end of the tubes into the adsorption section. The adsorbent flows downwardly through the adsorption section, through a feed gas engaging section having a construction similar to that of the disengaging section previously described, through a rectiiication section, through another disengaging section, and subsequently into the tubular desorption section. The feed gas is introduced into the adsorption section through the feed gas engaging section, the more readily adsorbable constituents are adsorbed on the adsorbent and flow downwardly with the adsorbent through the feed gas engaging section, and the less readily adsorbable constituents flow upwardly through the adsorption section and are removed from the adsorbent bed through the disengaging section situated just below the cooling section. The adsorbent containing the more readily adsorbable constituents flows downwardly eventially into the desorption section wherein the adsorbed constituents are removed from the adsorbent forming a lean adsorbent andthe desorbed constituents pass upwardly into the disengaging section directly above the desorption section and are removed from the system.

The multiple tray and adsorption section of special construction in my improved selective adsorption process comprises an adsorption section containing a multiplicity of adjacent and sep- 5, arate adsorption zones disposedA in vertical relationship in the selectivey adsorption tower. Each of these Zones is provided with individual feed gas engaging and lean gas disengaging sections. They adsorption zones are so-arranged so that each receives cooled lean adsorbent from above and each discharges rich adsorbentsaturated with the more readily edsorbable constituents of the feed gas through the rectification section and into the desorption section situated below. The lean adsorbent, removed from the desorption section after removal of the adsorbed constituents, is introduced into the cooling section in the upper portion of the selective adsorption tower and l cooled in the cooling section to a temperature suitable` for adsorption.

The process and apparatus of my invention may be more clearly understood by reference to the accompanying drawings in which,

Figure 1 is a diagrammatic illustration of the apparatus in which my improved selective adsorption process may be carried out, and

Figure 2 is a diagrammatic illustration showing in detail the adsorption section of special construction. In Figure 2 the multiple tray adsorption section is shown to include three adsorption zones each provided with separate inlets and outlets for gas ow and with separate inlets and outlets yfor adsorbent flow.

Figure 3 is a diagrammatic illustration of one modication of charcoal flow controllers lill and I I2 of Figure 2.

In the following description of'my invention the process and apparatus will be more fully described for purposes of greater clarity as employing charcoal as the adsorbent and utilizing as feed 110,000 m. s. c. f./d. of a specific gaseous mixture of the lower molecular weight hydro-4 carbons .having the following composition:

Volurn Rate Component m S` Q fl/d Methane 94. O 103, 400 Ethane. .0 3, .300 Propane 7 770 Butanes, and hea .3 2, 530

Vhaving the following composition:

Volume Component Per Rami v Cent m. s. c. ./d

Methane 99. 5 103, 200 Ethane 0. 4 320 Propane 0. 1 80 IThe methane recovery is better than $9 volume percent.

6,300 m. s. c. f./d. oi a rich Igas containing iii) 6 I the more readily adsorbable constituents is produced having the following composition:

Volume Rate Component gt m. s. mild'.

' 3. 2 200 Ethane 45. 7 2, 880 Propane.. 11.0 690 Butane and heavier 40. l 2, 530

adsorption section of my invention. As indicated in Figure 1 the multiple tray adsorption section consists of three adsorption zones--I6, Il and I8, one placed above the other.

The charcoal flows through the system at a rate of 420,000 pounds per hour controlled by solids feeder is positioned directly below desorption section l Solids feeder I9 discharges charcoal into bottom Zone in which is maintained a charcoal level 2l by means of charcoal valve 22 and level control 22a positioned in outlet line 23 fromfthe bottom of adsorption tower I0. The charcoal flowing through valve 22 flows` down-, wardly by gravity through transfer line 24 and is introduced into charcoal lift line 25 where it meets an upwardly flowing stream of gas forming a charcoal-gas suspension. Under a pressure induced by lift gas blower 26 the suspension is elevated through lift line 25 to impactless separator 2l located at a point somewhat higher than the upper end of adsorption tower I0. Be-

cause of the greater cross-sectional area providedin separator 2l for gas ow, the gas-charcoal suspension is broken and the granular charcoal ilows as a continuous phase together with the separated gas through transfer line 28 and is introduoed, into charcoal hopper II in the -upper portion of adsorption tower I il. The temperature of the charcoal as it is introduced into hopper I I is quite high, varying between about 200 F. and 600 F. depending upon the type of feed stock being separated. This hot charcoal news down- ,f wardly through the tubes contained in cooling section I2 wherein it is cool-ed by indirect heat exchange with cooling water or other suitable cooling medium owing outside the tubes. The charcoal ilowing from cooling section I 2 has been cooled at a temperature varying between about 90 F. and 175 F. rendering it suitable for repassage through adsorption zones I6, Il and I8.

The gaseous mixture to be separated, having the analysis previously given and containing a relatively small proportion of constituents which are more readily adsorbable by the charcoal, is introduced at a pressure of 550 pounds per square inch gauge into selective adsorption tower I0 by means of line 30. A certain amount of gaseous reflux, consisting of a gas desorbed in rectification section I3 which contains a high concentration of methane togetherwith some of the more readily adscrbable constituents of the gaseous mixture is combined with the gaseous mixture in line 30 by means of line 3| controlled by valve 32 to form an enriched feed. The enriched feed ilowing through line 33 is divided into three approximately equal fractions one each of which is introduced into one of the three adsorption zones I6, I1 and I8 by means of lines 34, 35 and 36, controlled by valves 31, 38 and 39, through engaging sections 60, 6I and 62, respectively. The particular construction of the adsorption zones, as hereinafter more fully described, substantially completely prevents the gas introduced into one adsorption zone from flowing into one or both of the adjacent adsorption zones. The enriched feed gas introduced into each of the adsorption zones` previously described iiows upward through the bed of downwardly flowing charcoal maintained in each adsorption zone and into the free space of disengaging sections 63, 64 and 65, formed between the upper surface of the charcoal bed and the tray immediately above in each adsorption zone. During passage of the enriched feed through the charcoal bed in'each adsorption zone the more readily adsorbable constituents, those heavier than methane and including those present in the original gaseous mixture together with those added as reflux to form the enriched feed, are adsorbed on the adsorbent in each adsorption zone to form a rich charcoal. The methane in the enriched feed, being less readily adsorbable than the higher molecular weight constituents, moves upwardly through the adsorption zones as a substantially unadsorbed gas and is removed as a lean gas from disengaging sections 63, 64 and 65. The lean gas is removed from adsorption zones I6, I1 and I8 by means of lines 40, 4I and 42, controlled by valves 43, 44 and 45, respectively. The three streams of lean gas thus removed are combined in header 46 and conducted by means of line 41 to cyclone separator 48 wherein traces of the granular adsorbent are removed from the lean gas stream. These traces of charcoal are removed from separator 48 by means of line 43 controlled by valve 56. The lean gas containing 99.5 volume per cent methane is removed from separator 48 by means of line I controlled by valve 52, across which is maintained a pressure drop of between about 5 and 50 pounds per square inch, and is removed from the system as substantially pure methane by means of line 53 and sent to storage or equipment for further processing, not shown, at a rate of 103,600 m. s. c. f./d.

A portion of the lean gas not removed from disengaging section 63 flows upwardly through the tubes of the upper tray of disengaging section 63, upwardly through the tubes of cooling section I2 serving therein to remove traces of moisture from the charcoal being cooled and to saturate the charcoal with methane. Subsequently, the lean gas passes upwardly through the charcoal in hopper Il into the free space in the upper portion of adsorption tower I8 where it is combined with lean gas separated in impactless separator 21 from the lean gas-charcoal suspension. The lean liit gas is removed from the upper portion of adsorption tower Il) by means of line which serves as a return line to lift gas blower 26 cornpleting the lift gas cycle. Because of the methane flowing upwardly through cooling section I2, line 16 is provided and controlled by valve 11 to remove accumulations of that gas in the lift gas cycle. Valve 11 discharges into line 53 on the low pressure side of valve 52 and allows a flow of methane through line 16 which is suflicient to maintain an upward now of methane through cooling section I2.

The rich charcoal formed in adsorption zones l I6, I1 and I8 through the adsorption thereon below solids feeder I9.

of the more readily adsorbable constituents of the enriched feed flows downwardly out of each adsorption zone and is introduced into rectication section I3. Herein the rich charcoal is contacted by additional quantities of the more readily adsorbable constituents which are liberated from the charcoal in desorption section I5 and flow upwardly countercurrent to the downwardly owing rich charcoal serving to desorb small quantities of methane from the rich adsorbent present in rectication section I3. The desorbed methane ows upwardly into disengaging section 66 from which it is removed by means of line 3| controlled by valve 32 and is introduced into line 38 together with the reiiuX stream described to form the enriched feed. The rectified charcoal present in reetiiication section I3 iiows downwardly through the tubes of rich gas disengaging section 61 and into steaming section I4 disposed directly above desorption section I5. In steaming' section Ill and in the upper portion of the tubes of desorption section I5 the downwardly flowing charcoal containing the more readily adsorbable constituents of the gaseous mixture is heated and contacted therein with a countercurrent stream of a stripping gas such as for example, steam. Because of the preferential adsorption of steam over that of nearly all other gases, the adsorbed constituents on the charcoal are desorbed when the steam is adsorbed on the charcoal and the thus desorbed constituents move upwardly through the tubes of desorption section I5 into rich gas disengaging section Si, and the adsorbed steam moves downward into the desorption zone with the charcoal. A portion of the desorbed constituents pass upward through the tubes of disengaging section 61 into rectification section I3 and serve therein as an internal reux to effect desorption from the adsorbent of small quantities of methane and are removed together with the methane from disengaging section 66 and used as reflux to form the enriched feed. The remainder of the more readily adsorbable constituents desorbed in desorption section I5 flow into the free space of disengaging section 61 and are removed therefrom by means of line 18 controlled by valve 1I and are removed from the system at a rate of 6300 m. s. c. f./d.

The charcoal containing the adsorbed steam is heated in desorption section I5 to a temperature sufficient to cause a substantially complete removal therefrom of steam which moves upward through the desorption section I5 to again cause adsorbed gas desorption in steaming section I4 completing an internal stripping steam recycle. A small amount of the stripping gas generally finds its Way upward through steaming section I4 and is removed together with the rich gas through line 18 and further small amounts of the stripping gas are adsorbed on and removed with the charcoal owing from the bottom of desorption section I5. In order to maintain the required amount of steam or other stripping gas in adsorption section I5, a small amount of the stripping gas is added by means or" line 18 controlled by valve 19 into bottom zone 20 situated In desorption section I5 When the more readily adsorbable constituents are removed from the charcoal in the upper portion thereof, steam or other stripping gas is adsorbed on the lean charcoal and ows down- `wardly with the charcoal through the desorption section into regions therein of higher temperature. A temperature is maintained in the lower portion of desorption section l which is sufi'lcient to cause substantially complete desorption of the stripping gas froml the charcoal so that the former will pass upwardly through the tubes of the desorption section and effect desorption of more readily adsorbable constituents iii-fthe u pper cooler portions of desorption section l5. The charcoal, thus freed of more readily adsorbable constituents and containing very small amounts of the stripping gas adsorbed thereon, passes downward through solids feeder IS, Vbottom zone 2U, line 23, controlled by charcoal valve 22 and through transfer line` 26 into lift line 25' for return to the upper portion of selective adsorption tower Il), thus completing the charcoal cycle. Charcoal valve 22 maintains a charcoal level 2l in bottom zone 2@ for two purposes: (l) to prevent the reverse flow of lean lift gas upward from lifty line 215 through transfer line 24, line 23 controlled by valve 22- into bottom zone 20 of adsorption tower lil which would cause contamination of the rich gas removed from the desorption section by the less readily adsorbable constituents contained in the lean lift gas; and, (2) to effectively prevent the downward now of steam or other stripping gas introduced into bottom zone 2l) from flowing downwardly with the charcoal into lift line 25, for such amounts of steam or other stripping gas have a tendency to collect on the charcoal inthe cooler portions of cooling section l2Y markedly altering the .flow characteristics of the charcoal Referring more particularly to Figure 2, wherein like parts are indicated with the same reference numbers as in Figure 1', a multiple tray adsorption section containing three adsorption zones is shown in a selective adsorption column.

feed/gas `isremoved as previously described Afrom the three `adsorption Zones .by means of vlines .diluer andr 42, controlled by valves .43,44 .and 4,5, respectively, into header 4d from which the methane is removed by means of line lill and .conveyed to charcoalk separating means, as Apreyiously described in conjunction with Figure 1, .or ltofeuquipment for fur-ther processing not shown. In order to control the quantity of gas flowing through the individual adsorption Zones I 6, l1 and I8, valvesA 153, Lid and 45, respectively, `,are actuatedby controllers `8D, `8l and 82, .which in turn are activated respectively by 'flowmeters 83, it and 85. An accurate control over the amount of gas flowing through each adsorption zonel in the multipletray-adsorption section is effected.

vllhelean charcoal `flowing downwardly `through the ytubesY in cooling section |2-is cooled by Iindirect heat exchange with water or other coolingmedium flowing outside the .tubes and is .saturated therein-.with methanezfrom the `leanngas ".Whchgiioyvs upwardly countercurrent.tothecharcoal :through the` cooling section as prei/ioiisly` described. The cooled charcoal `flows bygravity into zoner which is formedfbetween lower tube sheet-st 4of cool-ine section fl 2 and primary trav :t8l .-offdisenaaeine--Seti m .53- -I-.ean eherealfis lo introduced from zone 85 into each adsorption zone of the multiple tray adsorption section in Y amanner which is described as follows:

Primary tray 88 of adsorption zone' I6 is provided with primary tubes 9!) extending down-1 ward therefrom through which flow cooled char= coal from zone S6. Introduced into the lower ends of primary tubes t@ and extending upward a short distance from the lower ends thereof are secondary tubes 9i of smaller diameter than that of primary tubes 9U. Secondary tubes S'l con-Vey cooled charcoal downward through and independent of adsorption zone I 6- into adsorption zones il i3 below. Cooled charcoal flows from Zone de downward through primary tubes 9@ therein dividing into two streams, the first of which nous through the annuli formed between primary tubes Si) and secondary tubes Si into adsorption zone Se, and the second which flows at approximately twice the rate as that of the first stream downwardly through secondary tubes si, through tubes 92 connected to secondary tubes 9S by means of couplings 93 and into adsorption Zones il and I8 immediately below. Couplings 93 are present in the tubular section consisting of tubes 9i and 92 in order to facilitate the assembling and dismantling of the adsorption section. Tubes 92 pass downward through and are independent of secondary tray 9@ and extend downward and are integrally attached to primary tray 9'5. Tray 95 in adsorption zone il is the equivalentv to primary tray 88 in adsorption Zone i6 immediately above. The cooled charcoal flowing through tubes 92 hows through primary tray 95 and again divides into two streams in primary tubes 96 attached to primary tray 95; Primary tubes 96 attached to primary tray 95 are analogous to primary tubes 96 attached to primary tray B8 in ,adsorption Zone I6 above. The charcoal flowing through tubes 95 divides into two Streams; the first flowing through the annuli formed between primary tubes 96 and secondary tubes Sl and flows into adsorption zone ll, the second flowing through secondary tubes 9i, and through tubes 98 attached to tubes Sl by means of couplings 9S. Tubes Q8 pass through and are independent oi secondary tray l, and continue downward and Ypass through and are integrally attached to primary tray lill in adsorption zone E18, tubes S8 extending downward below primary tray Il a short distance into adsorption Zone IS. Thus, in the manner just described, lean cooled charcoal is introduced individually in separate streams into the three separate adjacent adsorption zones i6, Il and I3. Primary tray 83 and the primary tubes S@ attached thereto form disengaging section 63 by means of which the lean gas consisting of lessreadily adso-rbable constituents of the gaseous feed are removed from adsorption Zone i6. Similarly, primary tray 35 inadsorption zone il and the primary tubes 963 attached thereto form disengaging section` 64 by means of which the fraction of .lean gas is removed from adsorption' zone Il. Primary tray lili in adsorption zone i3 together with extensions therethrough of tubes 98 form disengaging section V from which isremoved the third fraction of lean lgas from adsorption zone i8.

During passage through each adsorption zone, the cooled charcoaly is contacted by a counter- ,75 current stream of` gaseous-feed together with 11 added reflux and substantially completely adsorbs therefrom the more readily adsorbable constituents together with small amounts of methane present in the enriched gaseous feed to form a rich charcoal.

through secondary tray 9d, through tertiary tubes ilZ attached thereto into feed gas engaging section 6d and onto primary tray S5 of adsorption zone l1. nterdisposed on primary tray 95 between primary tubes 96 in a geometrical pattern and integrally attached thereto are Quaternary tubes |03. Each of the quaternary tubes |63 on primary tray 95 is disposed directly below each of the tertiary tubes |02 which are attached to secondary tray 9d directly above. Thus, the charcoal flowing downwardly from adsorption zone Iii, through tertiary tubes |32 into engaging section @D continues its downward flow through quaternary tubes |03 attached to primary tray 55 of adsorption zone il' and downwardly through and independent of adsorption zone I1 by means of Quaternary extension tubes il connected to Quaternary tubes H33 by means of couplings IE5. Quaternary extension tubes |64 pass downward through and are independent of secondary tray I of adsorption zone |1. lThe rich charcoal formed in adsorption zone VE passes downward through secondary tray itil, through the annular spaces formed between quaternary extension tubes |04 and tertiary tubes m5, which latter are integrally attached to sec ondary tray IESE) and are similar to tertiary tubes |62 attached to secondary tray 94 above in engaging zone it above, and passes into engaging section-| and onto primary tray ESI. Integrally attached to primary tray |il| and extending downward therefrom an equal distance as do tubes 98 previously described are charcoal now controllers 01. The function of charcoal flow controllers |511 which are situated directly below the quaternary extension tubes itil and tertiary tubes It, is to determine the rate of charcoal ow through adsorption zones l5 and I1'. Because the rate of solids ow through a vertical tube is almost exclusively proportional to the cross-section area open to solids flow, the determination of the rate of charcoal flow through both of the adsorption zones previously mentioned is easily accomplished by the design of the charcoal ow controllers |01 so that the cross-sectional area of the annular spaces between Quaternary extension tubes It@ and the upper portion of charcoal flow controllers |61 is the same as the internal cross-sectional area of quaternary extension tubes |64. Thus, the rate at which charcoal ows out of adsorption zone le downward through tertiary tubes |62, quaternary tubes m3, extension tubes |64 and into charcoal flow controllers lill' is the same as the rate at which charcoal passes downward from adsorption zone |1 through the annular spaces of tertiary tubes |i into charcoal flow controllers lill. The rich charcoal flowing downwardly through charcoal flow controllers |01, which are integrally attached to primary tray |0| of adsorption zone IS, continues to flow downward through adsorption zone i8 through extension tubes itt attached by means of couplings Ia to the lower extremity of flow controllers |91. Extension tubes |98 extend downwardly through tertiary tubes m9, which are integrally attached to secondary tray |||l, to a point on a level with tray The rich charcoal formed in adsorption zone I8 flows downwardly through the annular The rich charcoal formed in adsorption zone l passes downwardly by gravity spaces formed between extension tubes |98 and tertiary tubes H39, into engaging section 62 and onto tray ill. Charcoal flows through each of adsorption zones i6, |1 and |8 at substantially equal rates; therefore, the quantity of rich char coal flowing downwardly through extension tubes los is substantially equal to twice the rate at which rich charcoal ows downwardly through adsorption Zone I8 through the annular spaces formed between extension tubes |88 and tertiary tubes |9. Thus, in the design of charcoal flow controller H2 integrally attached to tray l l l, the cross-sectional area of the annular spaces between the upper portion of charcoal flow controllers I2 and extension tubes |03 is made to be equal to one-half the cross-sectional area of extension tubes 68. The rate of charcoal flowing downward from adsorption Zone i8 through tertiary tubes its@ and into charcoal ow controllers l2 is controlled by the cross-sectional area of the annular spaces in the controllers to a value which is equal to the rate at which charcoal ows through adsorption Zones |S and I1, or equal to one-half the rate at which charcoal flows downwardly through tubes analogous to extension tubes |03. The rate of charcoal flow from the Vlower portions oi the charcoal flow controllers H2 and sealing legs ||2a integrally attached to tray is approximately three times the rate of charcoal flow through each adsorption zone and is equal to the rate of charcoal flow from zone 8% through primary tubes 99 attached to primary tray 38. An upward flow of desorbed methane and reflux countercurrent to the charcoal flow exists through charcoal flow controllers H2, and sealing legs ||2a. A pressure drop in the upward direction is thereby produced and use is made of this in order to cause the ow of the desired quantity of reflux from sealing leg section t6 through line 3| controlled by valve 32 into venturi 9 which aids in forcing the reflux into line 30 wherein it is combined with the feed gas to form an enriched feed.

The charcoal flow controllers |01 on primary tray lill and charcoal ow controllers |2 on tray may be constructed in a variety of modications, all of which are based upon the principle that the flow of small granular solids through an orifice or a tube is primarily dependent upon the cross-sectional area open to solids flow. The height of solids above the orice or the lower opening of the tube exerts a negligible influence on the flow rate.

Referring more particularly to Figure 3 there is shown one modication of charcoal ow controllers |01 and H2. The indicating numerals shown therein refer particularly to charcoal flow controller H2, however, a similar construction may be used in charcoal flow controller |01 andany others included in installations where more than three adsorption zones are used. Extension tube |08 is shown extending downward through and integrally attached to tray Tubes |24, which are also integrally attached to tray and extend downward therefrom for a distance equal to the distance to which tube |08 extends downward from tray are arranged around extension tube |8 in a regular geometrical pattern. Disposed between tubes |24 and extension tube |98 is baille |20 which separates the charcoal flowing downward1y through tubes |24 from the adsorption zone immediately above,

' from the charcoal flowing downwardly through tube |08 which flows from other adsorption zones above that adsorption zone immediately 'ga'ging and adsorption sections "escobas 13 above tray Arranged around the vertical axis of tube its in substantially the same geometrical pattern are tubes |22 which are disposed between plate |2| and annular ring plate |23 so that the charcoal owing downwardly through tubes |24 continues on through tubes |22 and the charcoal flowing downwardly through tube IBB i'ills the space below the annular ring plate |23- bailie |20 combination and plate 12|. Interdisposed between tubes |22 at regular intervals `are perforations |22a on plate 2| and which have diameters equal to the diameter of tubes |22 and through which flows the charcoal which 'enters the charcoal now controller through tube i8. The two individual charcoal flows are here coinbined and flow downwardly through sealing leg ||2a into rectification section I3 as previously described. The actual charcoal iiow rate cohtrolled through tube its is controlled by the total cross-sectional area of the perforations `|22an plate |2| which are interdisposed between tubes |22, and the charcoal flow rate through tubes 52d from'the adsorption zone immediately above tray is controlled by the internal cross-sectional passes upward through plate "|2i as shown 'in Figure 3, through tubes l2 la, upward and around the upper portion of baiile i2, and upward through tubes |2 through tray Hi into. the enimmediately above. In this manner the eiiect of the'upwardly flowing gas upon the downwardly iiowing carbon in iiow controlling tubes |22 and periorations |22a is minimized. When applying this modification to a charcoal iiow controller as shown as charcoal ilow controller |2 in Figure 2., the ratio between the internal cross-sectional areaoftubes |22 and the perforations i22u interdisposed 'in plate |2| between tubes |22 should be 1 'to L2 because the charcoal iiowing rthrough 'the r'perforations |2'2c at a flow rate'which is substantially twice as great as the flow rate 'through tubes |22 when equal. charcoal flow rates through each adsorption zone is desired. I.In the case of charcoal flow controller lill the ratio ofthe crosssectional areas between tubes |22 andthe perforations |22a in plate |21 disposedbetweentubes |22 should be 1 to 1. Obviously other modifications of the charcoal flow controller shown in Figure 3 may be Vutilized to control the'rati'o of charcoal or any granular solids flow by a lsuitable ratio of cross-sectional areas. VIt should be understood that this is merely one illustration of a` construction suitable for the control of the ratio of solids now and that other ip-ieces Vof apparatus based upon the same principle are applicable as well.

The enriched charcoal removed from each of the adsorption zones disposed in the multiple tray adsorption section is combined in charcoal flow controllers H2 attached to tray with 'the attached sealing leg shown which extend downward from tray and forms disengaging and sealing leg section et. lThe enriched charcoal iiows downwardly from the lowerportion of the charcoal -flow `controllers 'through recti'cation y v.section i3, and through rich gas disenga'gng section 67. The drawing shows two rectication sections, namely I3 and |3a, to provide for re moval of a side-cut if desired, as explained below; but it is Vto Ybe understood that if no side-cut is' desired, section Ita with its disengaging section including ll3a, ||4a, 67a, 'ica and ila may be omitted or not used. Rich gas disengaging section comprises tray H3 to which are integrally `'attached tubes lill. The rich charcoal flowing through disengaging section 61 news through steaming section lll and downward through the tubes of desorption section |5. The rich charcoal vpassing therethrough is heated by indirect heat exchange and contacted with a countercurrent stream of a stripping gas such as for example steam, thereby causing the desorption from the rich charcoal of the adsorbed constituents contained thereon. The mechanism of desorption and 'rectication has previously been described in conjunction with the description of rectification section i3, steaming section lf3 and desorption section I5 shown in Figure 1.

It is to be understood in consideration of the description of the illustrations just described that any number of adsorption zones may be included within the multiple tray adsorption section to which my invention is directed, and the fact that three adsorption zones have been described must not be taken as limiting my invention. Multiple tray adsorption sections may be constructed containing as few as two and as many as four or more adsorption zones, depending upon the particular installation and the particular type of gaseous mixture which it is desiredto separate.

Should fractionation of the rich gas containing ethane, propane, butanes and heavier be desirable, a second rectification section maybe in-l cluded above the desorption section which will `permit a separation between any twoV of the constituents or the rich gas. Such a rectification zone would be situated above the rich gas disengaging section B1. The enriched charcoal ows through the feed gas engaging section into the rst rectification section l3nt. Here any adsorbed methane is desorbed by contacting the charcoai vwith a stream of ethane or heavier `llydrocarbons which are desorbed from the charcoal in the scce ond rectication section I3 wherein the charcoal is contacted with a reflux of propane or heavier hydrocarbons. The rich gas under these conditions of operation would consist of propane and 'heavier hydrocarbons while the side cut removed from a disengaging section die below the feed. 'engaging section would comprise the ethane and minor amounts of methane and Cs contaminants..

Plate ||3a and tubes iisd form the disengaging section sla from which the side-cut is withdrawn through line lila, and valve lid. A higher degree of fractionation may be obtained with more co1nplex gaseous mixtures by inclusion of'a vkmulti aandoet .activated granular charcoal with granules ranging from to 14 mesh in size. However, I do not wish to be limited thereby, because in certain specic applications granules as large as about 2 -mesh are applicable and in some cases powdered tenance and operation at elevated pressures, the `use of the gas lift system shown in the example is to be preferred.

It is to be understood that the present invention resides primarily in an improved selective adsorption process and apparatus whereby gaseous mixtures containing relatively small amounts of the higher molecular weight constituents, for example, from traces of these components to about 30 volume per cent, may be eiiiciently and conveniently separated without the disadvantages inherent in conventional separation processes. Thus, any modification may be made in the particular method in which the adsorption, pretreatment, or subsequent treatment is carried out Without departing from the basic invention herein disclosed.

TheY multiple-tray adsorption apparatus of my invention performs equally as well with other ysolid adsorbents such as silica gel, activated alumina, various adsorbents formed from iron and chromium oxides, the zeolites, etc., as it does vwith charcoal, and my invention is, therefore, in-

dependent of the type or character of the adsorbent used.

Having described and illustrated my invention and realizing thatn many modiiications thereof may occur to those skilled in the art without departing from the spirit or scope of my invention,

I claim:

1.. A process for the continuous separation of a gaseous mixture'by selective adsorption which comprises simultaneously contacting said gaseous mixture with a moving bed of granular solid adsorbent flowing downwardly through each of a multiplicity of separate adsorption zones, adsorbing on said adsorbent in each of said separate adsorption zones the more readily adsorbable constituents of said gaseous mixture to form a rich adsorbent, removing from each of said adsorption rones the less readily adsorbable constituents of said gaseous mixture as a lean gas, flowing said rich adsorbent from each of said .separate adsorption zones to a desorption zone, tdesorbing from said rich adsorbent therein the ,more readily adsorbable constituents of said gasqeous mixture, and removing the thus desorbed constituents from said desorption zone as a rich gas.

2. A process for the continuous separation of a. gaseous mixture containing constituents of varying adsorbability by selective adsorption which comprises simultaneously contacting said gaseous mixture with a downwardly moving bed of granular solid adsorbent in each of a multiplicity of separate adsorption zones, adsorbing on said adsorbent in each of said separate adsorption zones the more readily adsorbable constituents of said gaseous mixture to form a rich adsorbent, removing from each of said separate adsorption zones the less readily adsorbable constituents of said gaseous mixture which are substantially unadsorbed to form a lean gas, flowing said rich adsorbent from each of said separate adsorption.

zones toa desorption zone, desorbing from said rich adsorbent therein the adsorbed constituents contained on said adsorbent to form a rich gas and a lean adsorbent, removing said rich gas from said desorption zone, removing said lean adsorbent from said desorption zone, and returning the removed lean adsorbent to each of said separate adsorption zones.

3. A process for the continuous separation of a normally gaseous mixture containing constituents of varying adsorbability by selective adsorption which comprises continuously owing a granular solid adsorbent downwardly by gravity successively through a cooling zone, simultaneously through each of a multiplicity of separate adsorption zones, and a desorption zone, introducing fractions of said gaseous mixture into each of said multiplicity of separate adsorption zones, adsorbing in each of said adsorption zones on the downwardly owing adsorbent the more readily adsorbable constituents of said gaseous mixture to form a rich adsorbent, removing as a lean gas from each of said separate adsorption Zones the less readily adsorbable constituents of said gaseous mixture as a substantially unadsorbed gas, owing said rich adsorbent downwardly from each each of said multiplicity of separate adsorption zones to said desorption zone, desorbing therein the more readily adsorbable constituents of said gaseous mixture adsorbed on said adsorbent to form a rich gas and a lean adsorbent, removing said rich gas from said desorption zone, removing said lean adsorbent from said desorption zone, and returning the removed lean adsorbent through said cooling zone to each of said multiplicity of separate adsorption zones.

4. A process according to claim 1 in which said granular solid adsorbent comprises charcoal.

5. A process according to claim 2 in which said granular solid adsorbent comprises charcoal.

6. A process according to claim 3 in which said granular solid adsorbent comprises charcoal.

7. A process for the continuous separation of a gaseous mixture containing constituents of varying degrees of adsorbability by selective adsorption which comprises flowing charcoal downwardly by gravity successively through a cooling zone and simultaneously into each of a multiplicity of separate adjacent adsorption zones, combining said gaseous mixture with a portion of a reliux of more readily adsorbable gas to form an enriched feed, introducing a fraction of said enriched feed into each of said multiplicity of adsorption zones, adsorbing therein the more readily adsorbable constituents of said enriched feed to form a rich charcoal, removing from each of said multiplicity of adsorption zones as a lean gas the less readily adsorbable constituents of said gaseous mixture as a substantially unadsorbed gas, flowing said rich charcoal from each of said multiplicity of adsorption zones downwardly to a desorption zone, heating therein said rich charcoal while contacting said rich charcoal With a stripping gas, desorbing thereby the more readily adsorbable constituents adsorbed thereon to form a rich gas and a lean adsorbent, removing rich gas from said desorption zone, and conveying said lean charcoal from said desorption zone through said cooling zone to each of said multiplicity of adsorption Zones.

8. An apparatus for the continuous separation by selective adsorption of gaseous mixtures containing relatively small amounts of the more readily adsorbable constituents which comprises an adsorption column provided with a cooling section, an adsorptionsectiox-i, and-a desorption sectionsaid adsorption-section containinga muitiplicity of superimposed separate adjacent adsorption Zones, means lfor passing-a separate portion of said solid adsorbent simultaneously through each fof said adsorption zones, fandfmeans for combining 'the separate portions from :each of said zones for passage Athrough said desorption and cooling sections.

9. An apparatus foi-fthe continuous'separation by selective adsorption on a granular `sol-id adsorbent of a gaseous mixturecontaining relatively small amounts of the Ymore readily adsorbable constituents which comprises an-adsorptionfcolumn provided with a cooling section near fthe top thereof, and successively therebe-low, fan fadsorption section, anda desorption lsection, saidadsorption section comprising a multiplicity -`olf superimposed adjacent separate adsorption zones, means 'for introducing a portion fof flean adsorbent from the cooling section into 'eaclfloi said adsorption zones linsaid adsorption seo'tiony-rneans for introducing -a fraction :of said gaseous mixture vinto each of 'said adsorption zones 4tlfiereby adsorbing the more readily adsorbable constituents of said gaseous mixture on said adsorbent to form a rich adsorbent, @means for :separating a lean gas `containing the'lless lreadilyadsorbable constituents of said lgaseousmiXture v-as a .sdbstan'tially unadsorbed gas from -each of saidadsorption zones, means 'for removing said rich ad'- sorbent from each of said adsorption zones'ata controlled rate, means 'for combining the Lrich adsorbent removed from-eachlof said adsorption.

zones and passing the combinedadsorbent'itofthe desorption section, means for removing 'Strom said desorptionsection a richgas*comprising the `more readily adsorbable constituents -desorbed i therein from said rich"adsorbent-'toffform .a -lean adsorbent, means for removing said Lleanadsorbent-ffrom said desorption,section-means .for-'suspending the removed lean adsorbent -i'n' a 'llii't gas comprising apart of said lean gas, means-ttor conveying the suspension of isaidv lean gas and said'lean adsorbentto 'separating means disposed above said cooling sectionfand. means `for .conducting said lean adsorbent lfrom :said separating lmea'ns ito said cooling' section :wherein lrsaidilean adsorbent l,

is vcooled prior to introductioniinto said fadsorp tionsection.

l0. An apparatus for theicontinuousseparation by selective adsorption `on a granular v*solid :adsorbentof a gaseous mixture-containingwonstituentsof Varying degrees'of adsorbability and .containing relatively vsmall amounts of the more readily adsorbable constituents kwhich?comprises an adsorption column provided with f a 'cooling' section, an adsorption section, fat ileastvfone rectie i cation section and a desorption section, said adsorption section comprising Ia multiplicity of separate adjacent adsorption 'zones disposed Etogether in vertical relationship in said .adsorption section and arranged so as to substantiallyeelim'inate the flow of gas from one Yzone 'to "thee-zones adjacent, means in Aeach of Esaid multiplicity of adsorption zones for introducing a lean adsorb ent, means `for 'combining 4atleast aportion of Va reflux gas containing said more 4readily -adsorbh able constituents with said lgaseous .fmiXtu-'ef'to form an enriched feed, `means for :dividingsaid enriched feed intoa multiplicity 'of -fraotions, means for introducingsaid fractions of soliden-'- riched "feed into :each of the Imultiplicity of ad-- sorptionzones disposed insaidadsorption.section therebyradsorbing the more readily fadsorbable uents of saidfraction of said enriched -feed asa substantially asnadsorbedg'as, means for thefre-L moval of said rich adsorbent -trornech-o Vsaid multiplicity of adsorption zones, means for -com` biniin'g the nenas-sorbentthusfremovesifmm each' of said multiplicity Aof adsorption 'zonesfrso as 'to control the rate -of adsorbent `iiow 4through each of said adsorption izones, `means for removing from said rectification section relatively small amounts-fof the Iless readily adsorbable constituents o'f said gaseous mixture contained insaid rich 'adsorbent andi-desorbed from ysaid rich ad# sorbent in said recticationfzone 'by contacting said Vrichadsorbenttherein with additionalduan tities-'of the more readily fads'orbableconstituent's of said `gaseous mixture,` means for removingfrom said desorption section a richgascomprising the most readily adsorbable constituents desorbeii` therein `by heating said Arich adsorbent and contacting said rich adsorbent Witha :stripping gas., to Tor-m ia v"lean adsorbent, `transfer means for ade-- moving said dean adsorbent from said desorption section, means for combining a portion of said lean gas Withsaid lean `adsorbent removed ifrom said desorption section to iforin alean gas-"lean adsorbent suspension, separating means posttionedabove ysaid :cooling section tofsepara'te said lean adsorbent'J-rom said lean gas `'in said `-:sus'pe'hw sion, connecting Ymeans yconnecting 'said transfermeans With said separating means, means con-'- necting said separatingmeans with Athe top oi" said adsorption column whereby theleafn adsorb-` ent separated in said tseparatingmeans is =re turned to said lcooling section, and means for dividing the cooled-lean adsorbent rinto a multi# plicity of fractions prior tothe introduction fo'f i each iraction of :said cooled lean adsorbent into portion of the lean 'tromone of said adsorption 'zones is passed -fthfrough `saiclcoo'li'ru;ozone cokuntercurrenttofthe adsorbent'itherein; '12. process according ito--clai'm -whiohzf adsorbent from at least two of 'the ladsorption zones Vlis passed througlha control .zone E'in ,which Y the adsorbent liow from reach zone llis' controlled bypassing the adsorbent through lcoir-istr-ictionsof xed area, and 'a 'gas flow iis passed through'ithe 1 control zone fcounterourren't to the adsorbent Without passing through =said -constri'ctio'ns-I 113. yAprocess tor .the vseparation `of-agas'eous mixture by selective vadsorption fon a vsolid Iad sorbent vrwhich comprises passing-said adsorbent successively 4through a 4cooling acne, simultane-- ous'ly through 'each-v of a multiplicity of Aseparate adsorption zones, a sealing yzone, -a rectificationvZonaand a;desorption'zoine,passingseparalsepor` ticnf'isy ofisaid gaseous-mixture 'through each -of said adsorption;zonessseparatolyiremoving-unadsorbed f gas'fromfeachfof 'said'radsorption `zones;desoidoing adsorbed l'gas from thel adsorbent einsai-dJdesorifii-v vsorbed gas lfand returning another fportion 5to-said rectication zone yto =ac`t as linternalreflux there a portion-thereof -withfthe :gaseous-mixture duced fintoeach adsorption zone. g

114i. nfprocessiforithe continuous separation-'fof '-1 a gaseous mixture containing constituents of varying degrees of adsorbability by selective adsorption on a solid adsorbent which comprises flowing said adsorbent successively through a cooling zone, simultaneously through each of a multiplicity of separate adjacent adsorption zones, a rectification zone and a desorption zone, combining said gaseous mixture with a reflux to from an enriched feed, dividing the enriched feed into a number of substantially equal fractions, introducing each of said fractions into each of said adsorption zones, contacting therein each of said fractions with a moving stream of adsorbent and thereby adsorbing the more readily adsorbable constituents of said fractions thereon to form a rich adsorbent, removing from each of said adsorption zones a lean gas comprising less readily adsorbable constituents of said fraction of said gaseous mixture as a substantially unadsorbed gas, combining the rich adsorbent from each of said adsorption zones, flowing the combined adsorbent through the rectification zone to the desorption zone, heating the rich adsorbent therein while simultaneously contacting it with a stripping gas and thereby desorbing the more readily adsorbable constituents of the gaseous mixture adsorbed thereon to form a rich gas and a lean adsorbent, removing a portion of the rich gas from the desorption zone, returning another portion ofthe rich gas to said rectification zone to act as internal reflux therein and serve to desorb a` less readily adsorbable reflux gas fraction, and removing the latter reflux gas fraction from the rectification zone and employing at least a portion of it as said reflux gas.

15. A process according to claim 14 in which the solid adsorbent is charcoal.

16. A process according to claim 14 wherein said stripping gas comprises steam maintained in said desorption zone as an internal stripping steam recycle stream.

l17. A process according to claim 14 wherein said more readily adsorbable constituents of said gaseous mixture comprise less than about 30 volume per cent of said gaseous mixture.

f1.8. A process according to claim 14 wherein said more readily adsorbableconstituents of said gaseous mixture comprise less than about 15 volume per cent of said gaseous mixture.

19. An apparatus for the continuous separation by selective adsorption of a gaseous mixture containing relatively small amounts of more readily adsorbable constituents which comprises an adsorption column provided with a cooling section, an adsorption section, and a desorptionsection, said adsorption section being provided with a multiplicity of superimposed separate adjacent adsorption zones, means in each of said adsorption zones for introducing a fraction of said gaseous mixture, means in each of said adsorption zones for removing a lean gas fraction consisting of a fraction of the less readily adsorbable constituents of said fraction of said gaseous mixture, means for passing a solid adsorbent through said column continuously, simultaneously and at the same rate through each of said adsorption zones, and means for passing lean gas from one of said adsorption zones through said cooling zone.

20. An apparatus for the continuous separation by selective adsorption on granular solid adsorbents of gaseous mixtures containing constituents of varying degrees of adsorbability and containing relatively small amounts of the more readily yadsorbable constituents which comprises anv adsorption column provided with a cooling section, an adsorption section, a rectication section, and a desorption section, said adsorption section being provided with a multiplicity of separate adjacent adsorption Zones, means in each of said adsorption zones for introducing a lean adsorbent, means in each of said adsorption zones for introducing a fraction of said gaseous mixture, means for removing from each of said adsorption zones a fraction of a lean gas containing a fraction of the less readily adsorbable constituents of said gaseous mixture, means for transferring to the rectification section from each of said multiplicity of adsorption zones a rich adsorbent containing the more readily adsorbable constituents adsorbed thereon, means for remov-` ing from said rectification section a small amount of reflux comprising less readily adsorbable constituents desorbed from said rich adsorbent therein, means for mixing the removed reflux with said gaseous mixture before introducing said gas into said adsorption zones, means for removing from said desorption section a rich gas comprising the more readily adsorbable constituents desorbed from said rich adsorbent, and means for returning a portion of said rich gas to said rectification section to desorb said reflux therein.

21. An apparatus for the continuous separation of a gaseous mixture by selective adsorption on a granular solid adsorbent which comprises an adsorption column provided with a cooling section, an adsorption section, a rectification section, and a desorption section together with disengaging sections disposed between said sections to permit the introduction or removal of gases therethrough, feeding means for introducing said gaseous mixture into said adsorption section, means for removing unadsorbed gas from said adsorption section, means for removing desorbed gas from said desorption section, means for removing a gaseous reux from said rectification section and mixing it with the gaseous mixture in said feeding means, sealing means for preventing substantial gas flow between said adsorption section and said rectification section, means for circulating the adsorbent in a solid moving bed successively through the above sections of said adsorption column, and means for controlling the rate of circulation at a single point in the lower part of the column, said adsorption section comprising a multiplicity of separate adjacent adsorption zones, means in each of said adsorption zones for introducing a portion of said gaseous mixture introduced into said adsorption section, means in each of said adsorption zones for removing unadsorbed gas as a lean gas from said adsorption section, means in each of said adsorption zones for introducing lean absorbent thereinto directly from said cooling section, and means in each of said adsorption zones for removing therefrom rich adsorbent and passing it directly to the sealing means.

22. An apparatus for the separation of a gaseous mixture by selective adsorption on a solid adsorbent which comprises a column containing a multiplicity of adsorption zones disposed vertically therein, a horizontal primary tray at the top of each adsorption zone, ya horizontal secondary tray at the bottom of each adsorption zonea series of vertically disposed primary tubes depending from each of said primary trays except the lowermost so as to form a gas disengaging zone, a series of vertically disposed secondary tubes of smaller diameter than said primary tubes and disposed in the same vertical axis, said secondary tubes passing through each o1 said zones except the lowermost, and extending upward into the primary tubes of the adjacent adsorption zone and downward to the primary tray of the next lower adsorption zone so that one portion of adsorbent may flow through the primary `tray and its primary tube into the adjacent adsorption zone while another portion of adsorbent ows through the secondary tube into a lower adsorption zone, and the lowermost of said secondary tubes extending through the primary tray of the lowermost adsorption zone so as to provide a gas disengaging zone, a series of vertically disposed tertiary tubes depending from each of said secondary trays so as to form a gas engaging zone, a series of Quaternary tubes of smaller diameter than said tertiary tubes and disposed in the same vertical axis, said quaternary tubes depending from the primary tray of each of said adsorption zones except the uppermost and the lowermost and extending downward to the primary tray of the next lower adsorption zone, a series of adsorbent flow controllers depending from each of said primary trays except the two uppermost, and having the same vertical axis as said tertiary tubes, each controller being adapted to receive and control the ow of adsorbent through the quaternary tube and the tertiary tube immediately above it, a series of extension tubes depending from said flow controllers and extending through the adjacent adsorption zone, the extension tubes in the lowermost adsorption zone extending through the secondary tray thereof to another series of ladsorbent ow controllers depending from a tray therebelow, the latter controllers being adapted to receive and control the flow of adsorbent through said extension tubes and also through the tertiary tubes of the secondary tray of said lowermost adsorption zone, feeding means for introducing said gaseous mixture into each of said engaging zones, means for removing unadsorbed gas from each of said disengaging zones, means for removing reux gas from below the tray below the secondary tray of the lowermost adsorption zone, and means for controlling the combined 110W of adsorbent from all of the adsorption zones at a single point below said adsorption zones in the column.

23. A flow controller for controlling the rate of flow of each of two streams of solid adsorbent ilowing downwardly therethrough by passing each stream separately through a W control means of constricted area, while permitting an upow of gas through the controller but not through said ow control means of constrcted areas, which comprises a horizontal upper tray, a vertical shel1 attached to the lower side thereof, an intermediate tray and a lower tray within said shell, a central adsorbent inlet for one stream of adsorbent, said central inlet passing through said upper tray to a point above said intermediate tray, a baille extending upward from said intermediate tray to a point above the lower end of said central inlet and surrounding said inlet so as to permit separate passage of the adsorbent from the central inlet through the zone between the upper and intermediate trays and into the zone between the intermediate and lower trays, flow control openings dispersed in a geometrical pattern in the lower tray to permit controlled passage of adsorbent therethrough, a series of secondary inlet tubes disposed in a geometrical pattern around said central inlet, said secondary inlet tubes depending from said upper tray and extending to a point above the intermediate tray, flow control tubes having the same vertical axis as said secondary inlet tubes, for passing the adsorbent admitted through said secondary inlet tubes from above the intermediate tray separately through the zone between the intermediate tray and the lower tray and through the lower tray, and gas by-pass tubes extending upward from the lower tray to a point below the upper tray but above the lower ends of the secondary inlet tubes.

CLYDE H. O. BERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,422,007 Soddy i July 4, 1922 1,702,311 Pantenburg Feb. 19, 1929 1,825,707 Wagner Oct. 6, 1931 1,836,301 Bechthold Dec. 15, 1931 2,349,098 Kiesskalt May 16, 1944 2,384,311 YKearby Sept. 4, 1945 

1. A PROCESS FOR THE CONTINUOUS SEPARATION OF A GASEOUS MIXTURE BY SELECTIVE ADSORPTION WHICH COMPRISES SIMULTANEOUSLY CONTACTING SAID GASEOUS MIXTURE WITH A MOVING BED OF GRANULAR SOLID ADSORBENT FLOWING DOWNWARDLY THROUGH EACH OF A MULTIPLICITY OF SEPARATE ADSORPTION ZONES, ADSORBING ON SAID ADSORBENT IN EACH OF SAID SEPARATE ADSORPTION ZONES THE MORE READILY ADSORBAABLE CONSTITUENTS OF SAID GASEOUS MIXTURE TO FORM A RICH ADSORBENT, REMOVING FROM EACH OF SAID ADSORPTION ZONES THE LESS READILY ADSORBABLE CONSTITUENTS OF SAID GASEOUS MIXTURE AS A LEAN GAS, FLOWING SAID RICH ADSORBENT FROM EACH OF SAID SEPARATE ADSROPTION ZONES TO A DESORPTION ZONE, DESORBING FROM SAID RICH ADSORBENT THEREIN THE MOER READILY ADSORBABLE CONSTITUENTS OF SAID GASEOUS MIXTURE, AND REMOVING THE THUS DESORBED CONSTITUENTS FROM SAID DESORPTION ZONE AS A RICH GAS. 